To assess the clinical significance of Körner's septum (KS) or petrosquamosal (PS) lamina in different chronic ear pathologies, a surgical and anatomic study was carried out, in which the significance of KS was assessed in various otologic diseases. Of 639 patients who underwent ear surgery between 1998 and 2001, 426 were included in the study. The diagnoses were chronic otitis media without cholesteatoma (COM), tympanosclerosis (TS), adhesive otitis media (AOM) and cholesteatoma (COL) in 160, 100, 70 and 96 patients respectively. The operative records of the patients were reviewed for the presence of KS. There was antral blockage by KS in all patients who also had Cog (the middle portion of the PS lamina). KS was mostly seen in cases of TS. The prevalence of KS was not significantly different when the result of the COM group was compared with that of the COL and AOM groups ( p>0.05). The prevalence of KS was significantly higher in patients with TS than in those with COM. Both antral and epitympanic blockages were more prevalent in cases of TS than in those of COM (chi(2) =3.9, p =0.04 and chi(2) =6.6, p =0.01 respectively). There is a significant association between the presence of KS and TS. Based on this finding, it is recommended that a mastoidectomy be performed in cases of severe tympanosclerosis in order to remove KS. How the removal of this anatomic impact will affect the natural course of the disease is still a question that needs further investigation.